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STATE OF ILLINOIS 

DEPARTMENT OF REGISTRATION AND EDUCATION 




Drying and Preheating Coals 
Before Coking 

Part 1. Individual Coals 



H. W. Jackman 
R. J. Helflnstine 



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ILLINOIS STATE GEOLOGICAL SURVEY 
John C. Frye, Chief URBANA 

CIRCULAR 423 1968 



fSBC 



DRYING AND PREHEATING COALS BEFORE COKING 
PART 1. INDIVIDUAL COALS 



H. W. Jackman and R. J. Helfinstine 



ABSTRACT 

A coal preheater capable of drying and pre- 
heating sufficient coal for one complete coal charge 
to the pilot coke oven has been designed and built 
in the Illinois State Geological Survey laboratories. 
Coking tests on high-volatile A, B, and C bituminous 
coals preheated to a maximum of about 450° F have 
indicated that preheating consistently reduces coking 
time and increases the potential coke making capac- 
ity of a coke oven. The strength of coke made from 
the individual high-volatile coals tested is consist- 
ently improved by preheating. Similar tests being 
made on coal blends such as those used commercial- 
ly to produce metallurgical coke will be described in 
a subsequent publication. 



INTRODUCTION 

The demand for metallurgical coke, coupled with high operating and replace- 
ment costs of coke ovens, has been responsible for a continuing interest in develop- 
ment of methods to increase the daily throughput of coal in ovens producing coke for 
blast furnace and foundry uses. 

Several ways to accomplish this objective have been proposed, including the 
construction of tall coke ovens, holding 27 to over 3 tons of coal, as compared with 
15 to 18 tons in the average present-day oven. Tall ovens have been developed and 
used in Europe, and several batteries are under construction or planned in this coun- 
try and Canada. 

Also planned is an increase in the oven coking rate by use of high density 
silica brick and thinner oven wall shapes, allowing more rapid transfer of heat from 
oven flues to coal. This combination of dense silica and thinner walls has been 

1 



2 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 423 

shown in experimental ovens to be effective in decreasing coking time with a cor- 
responding increase in coke making capacity per oven (Price and Palumbo, 1965). 

Still another way to reduce coking time and increase coke production would 
be by drying and preheating coal before charging to coke ovens. Although such pre- 
heating facilities are not yet available commercially, coke-oven builders are con- 
sidering how this might be accomplished safely and economically. At least one coke 
oven battery in the United States has been equipped to preheat coal experimentally, 
and it is reported that a procedure for partially drying and preheating coal before 
coking is being developed in Japan (Yoshida, 1967). 

When coke producers became aware that coal preheating with significant re- 
duction in coking time might become a commercial possibility, the Illinois State Ge- 
ological Survey received inquiries regarding the effects of preheating Illinois coals 
and blends in which they are used. Although the U. S. Bureau of Mines had pub- 
lished valuable information on their experiences with preheating certain coals, in- 
cluding one from Illinois (Smith et al., 1956), it was decided to design and build 
an experimental preheater with a capacity to dry and preheat sufficient coal for one 
complete charge for the Geological Survey' s 17-inch pilot coke oven (Jackman et al., 
1955). Investigations then could be made on the effects of preheating any Illinois 
coal or coal blend that might be of interest to the Chicago or St. Louis steel industry, 



COAL PREHEATER 

The coal preheater consists of an enclosed steel cylinder with a conical dis 
charge end, which rotates in an electrically heated oven (fig. 1). The cylinder is 
36 inches in diameter, 5 7 inches in length, including the cone, and has a capacity 
of about 24 cubic feet. A 700-pound charge of coal at normal moisture occupies 
slightly more than half the total capacity. 

The cylinder, or drum, rests on power-driven rollers within the oven and is 
rotated at one-half revolution per minute. Eight lifting fins, which are welded to 
the inside surface of the drum, cause the coal to mix continuously as the hottest 
coal from near the heated surface is moved toward the center. 

Temperature within the heating oven is normally controlled at 5 00° F. A 
thermocouple extending into the center of the drum is used as the sensing element 
to a temperature recorder-controller. The controller cuts off the heat to the oven 
at any predetermined temperature. The total time required for preheating has var- 
ied from 3| to 7 hours, depending upon the moisture content of the coal and its 
final temperature. 

Coal moisture, which is driven off during the heating period, is released 
through a pipe extending from the drum and oven. A water seal at the end of the 
pipe prevents passage of air into the preheating drum if the temperature within the 
drum should fall and thereby create a partial vacuum. The properties and yields 
of coke and tar produced have demonstrated that there is little, if any, oxidation 
of the coals during preheating. 

After preheating to the desired temperature, the drum is lifted out of the 
oven and weighed to determine the percentage weight loss of the coal during pre- 
heating. This loss is assumed to be largely water and is subtracted from the orig- 
inal coal moisture to determine the moisture content of the coal as charged to the 
coke oven. At preheating temperatures above 35 0° F, this weight loss may exceed 
the ASTM moisture content of the original coal by 0.5 to 1.5 percent, indicating 



DRYING AND PREHEATING COALS BEFORE COKING 




Figure 1 - Coal preheating drum and preheating oven. 



ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 423 



some small loss in volatile matter or water of hydration not usually driven off in 
the ASTM moisture test. 

After weighing, the drum of preheated coal is suspended over the coal 
charging hole in the top of the coke oven. A sliding valve is drawn and the coal 
drops quickly into the oven with little contact with air. The drum is then lifted 
from the charging hole, and the lid to the charging hole is replaced. The coal in 
the pilot oven is leveled by hand through the leveling bar hole in the oven door. 
More coal is charged into the oven than is required to fill to the proper level, and 
the excess is raked out while leveling and is deducted from the total weight of 
coal charged. 

Acknowledgments 

We wish to acknowledge the assistance and cooperation of the coal and 
coke producers during the construction of the preheater and auxiliary equipment 
and for their further interest in the investigation by supplying the coals that have 
been tested. Those companies cooperating include the Bell and Zoller Coal Co., 
Freeman Coal Mining Corp., Granite City Steel Co., Indiana Gas and Chemical 
Corp., Inland Steel Co., Interlake Steel Corp., Old Ben Coal Corp., Sahara Coal 
Co., and Wisconsin Steel Co. 



TEST PROGRAM AND COKING PROCEDURES 

Five coals have been tested to determine the effects of preheating shown 
in this report. Included are three high-volatile B bituminous coals and one high- 
volatile C bituminous coal from Illinois and one high-volatile A bituminous coal 
from West Virginia. Tests are in progress on blends of high- and low- volatile 
coals such as are used commercially for metallurgical coke. Test results on blends 
are not included in this report, but will be discussed in a second publication. All 
coals tested were washed and prepared at the mines with top size not over 3 inches 
and bottom sizes ranging from one -quarter inch to zero. Coal analyses are shown 
in table 1 . 

Each coal is first coked in the moist condition, as received from the mine. 
Next, it is air dried at room temperature and coked and tested to determine the ef- 
fects of this surface drying. A third coking test is made after partially heat drying 
the coal in the preheater. For this test, the coal is heated to 210° F and is held 
at this temperature while the drum rotates for 2 hours. These coking tests are fol- 
lowed by others in which the coals are first preheated to approximately 250°, 350°, 
and 450° F. 

All coals are coked at the same oven flue temperature and under identical 
operating conditions. Changes in the times required to coke and in the physical 
properties of the cokes are assumed to be due to the increased rate of coking as 
coal moisture is eliminated and as the temperature of the coal is increased by pre- 
heating. Data from coking tests have been plotted and curves drawn to illustrate 
graphically the effects of drying and preheating. 

The pilot coke oven, which is 17 inches in width, holds 675 pounds of coal 
at normal moisture, having a dry coal bulk density of about 46 pounds per cubic 
feet. The oven walls, which until recently were built of silicon carbide brick 4^ 
inches thick, have been replaced with the same thickness of fire clay brick. With 



DRYING AND PREHEATING COALS BEFORE COKING 



TABLE 1 - ANALYSES OF COALS TESTED 



Type 


Coal 


Moisture-free basis 


Free- 
swell- 
ing 
index 


Maximum 
Gieseler 
fluidity 
(dial div 
per min) 


Moisture 


Volatile 

matter 
(%) 


Fixed 

carbon 

(7o) 


Ash 
(%) 


Sulfur 
(%) 



High- 
volatile C 
bituminous 


111. No. 


6 


13.9 


44.6 


48.0 


7.4 


2.30 


3h 


920 


High- 
volatile B 
bituminous 


111. No. 
111. No. 
111. No. 


5 

6-A 

6-B 


8.5 

9.3 

10.0 


36.8 
39.7 
37.9 


55.6 
53.0 
55.2 


7.6 
7.3 
6.9 


1.50 
1.28 
1.02 


5 

3% 

5 


103 
53 
15 


High- 
volatile A 
bituminous 


Eagle 




3.2 


35.1 


61.1 


3.8 


0.73 


9 


26,600 



Analytical data by the Coal Analysis Laboratory. 



this change, the oven is now operated at a constant flue temperature of 2300° F so 
that coals at normal moisture are coked at a rate of about 1.0 inch per hour. The 
coking period is considered to be that time from the moment the coal is dropped 
into the oven until the temperature at the center of the coke bed reaches 1775° F. 
Coke is then pushed, quenched, dried, sized, and tested. In addition, a contin- 
uous record is made of the pressure exerted on the oven walls by the coal during 
carbonization. 

The pilot coke oven is not a precision testing device. The data given 
should not be considered as an exact measure of performance, because the tests 
for coke strength, size, and gravity are empirical and adequate sampling is diffi- 
cult. Therefore, the curves drawn do not always intersect the plotted points, but 
are meant to show the most probable trends of the properties being determined. 



RESULTS 



High-volatile C Bituminous Coal from Illinois 



It can be assumed that preheated coal cokes rapidly because of less mois- 
ture to evaporate and higher coal temperature as charged to the coke oven. It fol- 
lows that drying and preheating very high moisture coal would cause the greatest 
reduction in coking time, provided this coal was preheated to the same temperature 
as other lower moisture coals. 

High-volatile C bituminous coal, mined over much of Illinois, is high in 
moisture. This coal is agglomerating, and much of it is higher in Gieseler fluidity 
than the high-volatile B bituminous coals from Illinois that are used for metallurgi- 
cal coke by the steel industry. A C-rank coal, with 13.9 percent moisture, was 
obtained from an underground mine in the No. 6 Coal in central Illinois. This coal 
was tested over the range of drying and preheating to determine the maximum re- 
duction in coking time that might be expected from an Illinois coal of this rank and 
moisture content. 



ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 423 



This C-rank coal was prepared for coking tests in the manner described pre- 
viously. The bulk density of the "as received" coal in the coke oven was 36.8 
pounds per cubic foot calculated to the dry basis. Coking by our standard operating 
procedure required 18 hours and 45 minutes. Subsequent air drying of a portion of 
this coal by spreading on the laboratory floor overnight reduced the moisture to 11.8 
percent. The bulk density of the air-dried coal, when subsequently charged to the 
coke oven, was increased to 40.4 pounds per cubic foot (dry basis), and the coking 
time was reduced to 1 8 hours. 

A third portion of this coal, heat dried in the preheater for two hours at 
210° F to 11.3 percent moisture, was coked in 17 hours and 10 minutes. Longer 
drying at this temperature would undoubtedly have driven off more moisture and re- 
duced the coking time still more. Examination of the "Coking Time" curve in figure 2 
indicates how further drying would probably have affected coking time. 

Following these initial drying studies, the C-rank coal was preheated to con- 
stant temperatures of 255°, 360°, and 428° F. In each case, the preheated coal was 
coked under the same oven temperature conditions. Coking time was reduced consis- 
tently to a minimum of 12 hours. This represents a reduction in coking time of 6 
hours and 45 minutes, or 36.0 percent. Considering this decrease in coking time 
and the increase in bulk density due to removal of surface moisture, it was computed 
that an oven battery operated on this coal preheated to this temperature could pro- 
duce 79 percent more furnace size coke than when operated on "as received" coal. 

Complete coking results of this series of tests are shown in figures 2 and 3, 
and in table A of the Appendix. Dry coal bulk density remained between 40 and 42 
pounds over the entire preheating range, expansion pressure was affected only 
slightly, and coke strength was increased consistently at the high preheating tem- 
peratures as shown by the tumbler test indices. 

In addition, the apparent gravity of the coke was reduced considerably by 
drying the coal, and it continued to drop at the higher preheat temperatures. Coke 
size increased as the coking time was reduced, which is contrary to normal coking 
practice. Furnace coke yield (plus 1-inch size) increased slightly, and the minus 
1 -inch screenings were reduced. The yield of tar remained practically constant. 
The fact that coke screenings were reduced and tar yield was not lowered indicates 
that very little, if any, coal weathering occurred during preheating. 

High-volatile B Bituminous Coals from Illinois 

A series of coking tests was made on each of three dried and preheated high- 
volatile B bituminous coals from Illinois. One was a No. 5 Coal and the other two 
No. 6. All of these coals are used commercially in blends for metallurgical coke. 
All are mined in the southern Illinois low-sulfur area, and all showed similar cok- 
ing trends when preheated and coked in the Geological Survey pilot oven. In this 
report, these No. 6 coals are identified as No. 6-Aand No. 6-B. 

Coking results with the Illinois No. 5 Coal are shown in figures 4 and 5 and 
in table B of the Appendix. Bulk density in the coke oven is seen to increase with 
air drying, and then remain practially constant. Coking time of the air-dried coal 
increased from 16 hours and 15 minutes to 17 hours and 15 minutes at this greater 
bulk density and then dropped to about 12 hours as preheat temperature was increased 
to 440° F. Expansion pressure increased, but not dangerously, at a low preheat tem- 
perature and then remained essentially constant The coke became stronger at the 



DRYING AND PREHEATING COALS BEFORE COKING 





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(111. No. 6). 



ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 423 





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Figure 3 



Results of coking tests on high-volatile C bituminous coal 
(111. No. 6). 



DRYING AND PREHEATING COALS BEFORE COKING 





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Results of coking tests on high-volatile B bituminous coal 
(111. No. 5). 



DRYING AND PREHEATING COALS BEFORE COKING 11 

faster coking rates, and the average size increased. The apparent gravity of the 
cokes remained constant after the coal moisture had been largely eliminated. 

Here, again, the yield of coke screenings was reduced slightly by preheat- 
ing and the tar yield remained practically constant, indicating that little or no 
weathering occurred during preheating. Reduction in coking time and the initial 
increase in bulk density resulted in a potential increase of 5 percent, or slightly 
more, in coke production at the highest preheat temperature used. 

Drying and preheating studies made with the two Illinois No. 6 Coals gave 
similar, although not identical, coking results, and these results were also simi- 
lar to those obtained with the No. 5 Coal. Results of the coking tests are shown 
in figures 6, 7, 8, and 9 and in tables C and D of the Appendix. 

Time required to coke each of the No. 6 Coals was reduced about 7 hours 
by preheating to 45 0° F. Dry bulk density of the coals in the coke oven remained 
essentially constant after air drying and removal of surface moisture. Expansion 
pressures exerted on coke oven walls were increased slightly with No. 6 -A Coal 
and considerably with the No. 6-B Coal. However, at no time did this wall pres- 
sure exceed 1.55 pounds per square inch. Coke strength and size were increased 
as the coals were coked more rapidly, and the specific gravity of the cokes tended 
to increase at the highest preheat temperature. Coke screenings were decreased, 
and coke oven capacity was increased approximately 75 percent. 

High-volatile A Bituminous Coal 

For comparison with the Illinois coals, a strongly coking high- volatile A 
bituminous coal from the Eagle seam in West Virginia was tested in the same man- 
ner as the higher moisture Illinois coals. This Eagle coal contained only 3.2 per- 
cent moisture as received, which was reduced by air drying to 2.0 percent. As 
with the Illinois coals, it was heat dried at 210° F, and subsequently preheated 
over the range 300° to 440° F before coking. 

Due in part, at least, to its low moisture content, this A-rank coal in the 
"as received" condition was coked in less than 15 hours. Air drying to remove 
surface moisture caused the dry bulk density to increase from 44 to 48 pounds per 
cubic feet and caused the coking time to increase to 16 hours and 15 minutes. 
Heat drying and subsequent preheating reduced the coking time to a minimum of 12 
hours, as with the B- and C-rank Illinois coals. Compared with the "as received" 
coal, this reduction in coking time was only 2 hours and 50 minutes. Expansion 
pressure increased very little. 

The tumbler stability index of the Eagle seam coke was fairly high at 44 
when coking the "as received" coal. This increased consistently to a maximum of 
52 when the coal was preheated to 435° F. Coke screenings decreased slightly, 
and the tar yield remained essentially constant. The potential coking capacity of 
the coke oven increased consistently as the preheat temperature was raised but 
showed only a 27 percent increase at 435° F preheat. Coking results are shown in 
figures 10 and 11, and in table E of the Appendix. It is interesting to note that 
this Eagle seam coal, when preheated to 435° F and coked by itself, produced 
coke having a tumbler stability index in the range of that required for metallur- 
gical coke. 



12 



ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 423 



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Figure 6 - Results of coking tests on high-volatile B bituminous coal 

(111. No. 6 -A). 



DRYING AND PREHEATING COALS BEFORE COKING 



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Figure 7 - Results of coking tests on high-volatile B bituminous coal 

(111. No. 6-A). 



14 



ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 423 





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Figure 8 - Results of coking tests on high-volatile B bituminous coal 

(111. No. 6-B). 



DRYING AND PREHEATING COALS BEFORE COKING 



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Figure 9 - Results of coking tests on high-volatile B bituminous coal 

(111. No. 6-B). 



16 



ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 423 



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Figure 10 - Results of coking tests on high-volatile A bituminous coal 
(West Virginia Eagle). 



DRYING AND PREHEATING COALS BEFORE COKING 



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Figure 11 - Results of coking tests on high-volatile A bituminous coal 
(West Virginia Eagle). 



ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 423 



SUMMARY AND CONCLUSIONS 

In response to requests for information regarding the effects of preheating 
on the coking properties of Illinois coals and coal blends, the Illinois State Geo- 
logical Survey has designed and built a coal preheater capable of drying and pre- 
heating sufficient coal for one complete coal charge to the pilot coke oven. Cok- 
ing tests on high-volatile A, B, and C bituminous coals dried and preheated over 
the range 210° to 450° F have indicated that preheating consistently reduces cok- 
ing time and increases the potential coke making capacity of a coke oven. All in- 
dividual coals tested to date have developed greater strength (tumbler stability in- 
dices) when preheated. Coke screenings (minus 1 inch) are reduced, and coke size 
is increased. Preheating tends to increase the expansion pressure exerted on coke 
oven walls, but no pressures considered dangerous have been encountered when 
coking individual high -volatile coals. 

This publication presents data obtained when coking individual coals. Sim- 
ilar data obtained when preheating and coking coal blends will be presented in a 
subsequent publication. 



REFERENCES 

Jackman, H. W. , Helfinstine, R. J., Eissler, R. L. , and Reed, F. H., 1955, Coke 
oven to measure expansion pressure — Modified Illinois oven: Blast Furnace, 
Coke Oven, and Raw Materials Proc, v. 14, AIME, p. 204-219; Reprinted 
as Illinois Geol. Survey Reprint Ser. 1955-E, 16 p. 

Price, J. G., and Palumbo, P., 1965, Greater coke oven productivity through accel- 
erated heating rates: Iron Making Proc, v. 24, TMS-AIME, p. 105-108. 

Smith, F. W., Girge, G. W. , Wolfson, D. E., and Reynolds, D. A., 1956, Better 
coke by the thermal pre treatment of coal: United States Dept. of Interior, 
Bur. Mines; presented at Annual Meeting of AIME, New York, 1956, 52 p. 

Yoshida, Susumu, 1967, Coking tests of the dried charging coal in coke ovens (in 
Japanese): Fuel Soc. Japan Jour. , v. 46, no. 484, p. 619-628. 



APPENDIX 



Tables A through E of this section present in tabular 
form the complete pilot plant coking results for each of the 
coals studied and described in this publication. Data include 
preheat temperatures, coking time, dry coal bulk densities, 
coke physical properties, yields of coke and tar, coal pul- 
verization, moisture in dried and preheated coals, and the 
effect of preheating on the capacity of coke ovens to produce 
coke. 

Table F shows the laboratory analyses of the cokes 
produced in each series of drying and preheating tests. 



DRYING AND PREHEATING COALS BEFORE COKING 



21 



TABLE A - RESULTS OF COKING TESTS ON HIGH-VOLATILE C BITUMINOUS COAL (ILL. NO. 6) 





Condition of coal 


As rec'd. 


Air dried 


Heat dried 
at 210° F 


Preheat 
at 255° F 


Preheat 
at 360° F 


Preheat 

at 428° F 


Run number 


1143 E 


1144 E 


1151 E 


1150 E 


1146 E 


1145 E 



Coking time (hr :min) 

Bulk density (dry coal 
lb per cu ft) 



18:45 



36.8 



18:00 



17:10 



39.6 



13:35 



40.6 



12:25 



12:00 



41.0 



Coke physical properties 
Tumbler test 
Stability 
Hardness 



Shatter test 


(7o) 


+ 2" 






+1V 






4-1" 






Sizing 


(%) 




+4" 






4" x 


3" 




3" x 


2" 




2" x 


1" 




1" X 


"2 




-V 






Average size 


(in.) 


Apparent gravity 



Coke yields (% of dry coal) 
Total coke (dry) 
Furnace (+1") (dry) 
Nut (1" x V') (dry) 
Breeze (-V) (dry) 



11.1 


11.4 


13.0 


20.5 


21.9 


25.3 


60.4 


60.7 


57.3 


55.0 


56.6 


56.6 


44.0 


42.0 


51.0 


59.2 


52.0 


62.0 


67.0 


63.4 


75.0 


76.0 


71.0 


88.4 


82.0 


81.0 


84.0 


88.0 


86.0 


90.0 


0.0 


0.0 


3.0 


5.5 


4.1 


7.0 


24.4 


25.1 


28.2 


31.6 


29.6 


29.6 


36.8 


37.7 


33.2 


32.9 


36.1 


37.0 


28.7 


27.3 


24.7 


20.9 


22.3 


18.5 


5.2 


6.0 


6.2 


5.4 


4.1 


3.8 


4.9 


3.9 


4.7 


3.7 


3.8 


4.1 


2.26 


2.29 


2.38 


2.54 


2.50 


2.59 


0.75 


0.71 


0.72 


0.715 





0.69 


63.4 


64.7 


65.5 


64.3 


64.3 


63.5 


57.1 


58.4 


58.3 


58.5 


59.1 


58.6 


3.2 


3.8 


4.1 


3.5 


2.7 


2.4 


3.1 


2.5 


3.1 


2.3 


2.5 


2.5 



Tar yield (gal dry tar: 
per ton dry coal) 



12.7 



10.7 



13.3 



13.5 



Expansion pressure 
(lb per sq in.) 

Pulverization (-1/8") 

Coke temperature (° F) 

°L moisture in coal as charged 

Coke oven capacity 

Coal charges/oven/24 hr 
Lb furnace coke/cu ft/ 

24 hr 
7<, increase in furnace coke 
(compared with coal 
"as received") 



0.3 


0.1 


0.3 


84.5 


88.8 


85.2 


1775 


1775 


1775 


13.9 


11.8 


11.3 


1.28 


1.33 


1.40 


26.9 


31.4 


32.3 



16.7 



20.0 



0.4 
85.1 
1775 
0.2 

1.77 
42.0 

56.1 



0.25 
84.8 



-1.5 



1.93 
47.6 



77.0 



0.45 
83.8 
1775 
-0.9 

2.0 
48.1 

79.0 



Minus values indicate weight loss on preheating greater than ASTM moisture value 



22 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 423 



TABLE B - RESULTS OF COKING TESTS ON HIGH- VOLATILE B BITUMINOUS COAL (ILL. NO. 5) 





Condition of coal 


As rec'd. 


Air dried 


Heat dried 


Preheat 


Preheat 


Preheat 


Preheat 








at 210° F 


at 225° F 


at 313" F 


at 433° F 


at 440° F 


Run number 


1117 E 


1118 E 


1119 E 


1120 E 


1121 E 


1122 E 


1129 E 


Coking time 
(hr :min) 


16:15 


17:15 


15:45 


15:10 


13:15 


12:10 


11:45 


Bulk density 
















(dry coal; lb 
per cu ft) 


40.6 


44.8 


44.0 


43.9 


46. 1 


45.2 


45.6 


Coke physical 
















properties 
















Tumbler test 
Stability 


24.3 


21.2 


23.7 


26.6 


33.9 


41.2 


41.2 


Hardness 


62.3 


66.4 


66.4 


65.5 


65.9 


65.7 


65.9 


Shatter test (7„) 
+ 2" 


48.0 


48.0 


46.0 


50.0 


56.0 


60.0 


52.0 


+1V 


75.0 


70.0 


71.0 


77.0 


80.2 


83.0 


81.0 


+1" 


95.0 


86.0 


88.0 


89.4 


91.2 


93.0 


93.0 


Sizing (7.) 

+ 4" 


4.3 


3.9 


2.9 


3.9 


5.9 


5.1 


3.8 


4" x 3" 


19.4 


18.2 


18.2 


20.7 


19.9 


25.1 


22.2 


3" x 2" 


41.7 


40.6 


42.6 


43.1 


44.6 


42.1 


44.4 


2" x 1" 


26.7 


29.0 


28.2 


25.2 


22.3 


21.3 


23.1 


1" x V 


4.2 


4.6 


4.7 


3.8 


3.8 


2.9 


2.8 


-V 


3.7 


3.7 


3.4 


3.3 


3.5 


3.5 


3.7 


Average size 
(in.) 


2.36 


2.31 


2.30 


2.39 


2.45 


2.51 


2.43 


Apparent 
gravity 


0.74 


0.775 


0.755 


0.765 


0.765 


0.76 


0.76 


Coke yields 
















(7. of dry coal) 
















Total coke 
(dry) 


69.0 


69.7 


69.1 


68.8 


68.4 


68.0 


68.2 


Furnace (+1") 
(dry) 


63.5 


64.0 


63.6 


64.0 


63.4 


63.7 


63.8 


Nut (1" x V) 
(dry) 


3.0 


3.2 


3.2 


2.6 


2.6 


1.9 


1.9 


Breeze (-V) 
(dry) 


2.5 


2.5 


2.3 


2.2 


2.4 


2.4 


2.5 


Tar yield 
















(gal dry tar; 
















per ton dry 
coal) 


10.4 


10.2 


12.4 


11.6 


11.6 


L1.0 


10.7 



Expansion pressure 
(lb per sq in.) 



Pulverization 
(-1/8") 


86.7 


83.4 


— 


81.0 


81.8 


82.5 


86.3 


Coke temperature 
(° F) 


1775 


1775 


1775 


1775 


1775 


1775 


1775 


7. moisture in ^ 
coal as charged 


8.5 


6.5 


5.5 


3.5 


-0.2 


-1.1 


-1.2 


Coke oven capacity 
















Coal charges/ 
oven/24 hr 


1.475 


1.39 


1.525 


1.58 


1.81 


1.975 


2.04 


Lb furnace coke/ 
cu ft/24 hr 


38.0 


33.9 


42.7 


44.4 


53.0 


56.8 


59.3 


7. increase in fur- 
















nace coke (com- 
















pared with coal 
"as received") 


— 


5.0 


12.4 


16.8 


39.5 


49.5 


56.1 



Minus values indicate weight loss on preheating greater than ASTM moisture values. 



DRYING AND PREHEATING COALS BEFORE COKING 



23 



TABLE C - RESULTS OF COKING TESTS ON HIGH- VOLATILE B BITUMINOUS COAL (ILL. NO. 6-A) 











Condition o 


f coal 








As rec'd. 


Air dried 


Heat dried 


Preheat 


Preheat 


Preheat 


Preheat 


Preheat 








at 218° F 


at 227° F 


at 270° F 


at 332° F 


at 370° F 


at 450° F 








Run numb 


er 








1111 E 


1112 E 


1113 E 


1114 E 


1115 E 


1134 E 


1149 E 


1161 E 


Coking time 


















(hr :min) 


17:40 


18:05 


17:00 


16:00 


14:30 


12:15 


11:30 


11:05 


Bulk density 


















(dry coal; lb 


















per cu ft) 


41.0 


43.5 


43.0 


42.9 


43.3 


43.6 


43.2 


43.4 


Coke physical 


















properties 


















Tumbler test 


















Stability 


16.4 


15.0 


18.0 


22.1 


28.0 


40.5 


40.7 


36.6 


Hardness 


61.8 


64.8 


65.7 


65.7 


64.6 


67.3 


66.2 


62.3 


Shatter test (7„) 


















+ 2" 


46.0 


45.0 


47.2 


41.0 


47.0 


56.0 


55.0 


57.0 


♦ IV 


73.2 


68.8 


76.2 


76.4 


80.8 


82.0 


84.0 


81.0 


+ 1" 


86.4 


86.0 


89.8 


87.8 


92.4 


93.0 


93.2 


93.0 


Sizing (%) 


















+ 4" 


0.0 


0.0 


0.0 


0.0 


0.0 


3.4 


2.3 


3.1 


4" x 3" 


15.1 


15.3 


15.1 


15.3 


19.8 


23.4 


23.7 


24.4 


3" x 2" 


39.4 


36.9 


42.7 


43.7 


45.3 


42.4 


44.2 


43.9 


2" x 1" 


35.7 


38.1 


34.8 


33.1 


27.7 


24.2 


23.4 


22.5 


1" x y< 


5.5 


6.2 


3.6 


4.3 


3.5 


3.2 


3.2 


2.9 


-y 


3.9 


3.5 


3.8 


3.6 


3.7 


3.4 


3.2 


3.2 


Average size 


















(in.) 


2.11 


2.08 


2.15 


2.17 


2.28 


2.43 


2.42 


2.46 


Apparent 


















gravity 


0.70 


0.73 


0.71 


0.715 


0.715 


0.72 


0.70 


0.745 


Coke yields 


















(% of dry coal) 


















Total coke 


















(dry) 


66.8 


67.5 


67.1 


67.6 


67.2 


67.5 


66.2 


68.0 


Furnace ( + 1") 


















(dry) 


60.5 


61.0 


62.1 


62.3 


62.7 


63.1 


61.8 


63.7 


Nut (1" x ',") 


















(dry) 


3.7 


4. 1 


2.4 


2.8 


2.2 


2.1 


2.2 


2.0 


Breeze ( — V ' ) 


















(dry) 


2.6 


2.4 


2.6 


2.5 


2.3 


2.3 


2.2 


2.2 


Tar yield 


















(gal dry tar; 


















per ton dry 


















coal) 


10.2 


10.4 


10.7 


10.75 


11.0 


11.0 


9.6 


10.6 


Expansion pressure 


















(lb per sq in.) 


0.2 


0.25 


0.3 


0.35 


0.4 


0.45 


0.35 


0.5 


Pulver iza t ion 


















(-1 '8") 


75.5 


81.2 


(Av 


erage of 81.0) 


79.2 


85.2 


88.3 


Coke temperature 


















(° F) 


1775 


1775 


1775 


1775 


1775 


1775 


1775 


1775 


°L moisture in 


















coal as charged 


9.8 


8.5 


7.7 


5.8 


1.4 


-0.3 


-0.5 


-0.7 



Coke oven capacity 



Coal charges/ 






oven '24 hr 


1.36 


1.33 


Lb furnace coke/ 






cu ft/24 hr 


33.7 


35.3 


% increase in fur- 






nace coke (com- 






pared with coal 






"as received") 





4.7 



1.41 1.50 1.65 1.96 
37.7 40.1 44.8 53.9 



2.09 2.16 



65.5 74.2 



Minus values indicate weight loss on preheating greater than ASTM moisture values. 



24 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 423 

TABLE D - RESULTS OF COKING TESTS ON HIGH- VOLATILE B BITUMINOUS COAL (ILL. NO. 6-B) 





Condition of coal 


As rec'd. 


Air dried 


Heat dried 
at 213° F 


Preheat 

at 230° F 


Preheat 
at 360° F 


Preheat 
at 440° F 


Run number 


1166 E 


1167 E 


1165 E 


1164 E 


1163 E 


1162 E 



Coking time (hr:min) 

Bulk density (dry coal; 
lb per cu ft) 

Coke physical properties 
Tumbler test 
Stability 
Hardness 

Shatter test (%) 
+ 2" 

+ 1V 

+ 1" 

Sizing (%) 

+ 4" 

4" x 3" 
3" x 2" 
2" x 1" 
1" x V 

-V 

Average size (in.) 
Apparent gravity 

Coke yields (7» of dry coal) 
Total coke (dry) 
Furnace (+1") (dry) 
Nut (1" x V) (dry) 
Breeze (-%") (dry) 

Tar yield (gal dry tar; 
per ton dry coal) 

Expansion pressure 
(lb per sq in.) 

Pulverization (-1/8") 

Coke temperature (° F) 

i 

% moisture in coal as charged 

Coke oven capacity 

Coal charges/oven/24 hr 
Lb furnace coke/cu ft/ 

24 hr 
7» increase in furnace coke 
(compared with coal 
"as received") 



19:30 



42.1 



18:35 



44.6 



16:55 



42.5 



16:05 



44.2 



6.8 



8.6 



13:15 



44.4 



9.9 



12:00 



43.5 



20.0 


20.3 


27.1 


32.5 


44.6 


43.9 


64.4 


68.0 


68.4 


68.2 


68.9 


66.4 


44.8 


37.8 


43.0 


45.0 


60.4 


55.2 


73.0 


74.0 


69.0 


80.8 


85.0 


80.8 


87.6 


86.0 


87.0 


90.0 


93.0 


91.2 


3.4 


2.3 


1.9 


2.3 


2.3 


1.3 


17.1 


13.4 


16.3 


14.6 


18.5 


20.3 


39.6 


41.0 


41.2 


44.2 


47.3 


49.0 


29.9 


34.2 


33.0 


31.4 


24.8 


22.6 


4.3 


4.1 


3.6 


3.7 


3.4 


3.1 


5.7 


5.0 


4.0 


3.8 


3.7 


3.7 


2.24 


2.15 


2.22 


2.23 


2.34 


2.3 


0.71 


0.74 


0.76 


0.75 


0.74 


0.71 


69.0 


69.9 


69.3 


69.2 


68.9 


71.2 


62.0 


63.5 


64.0 


64.1 


64.0 


66.3 


3.0 


2.9 


2.5 


2.5 


2.3 


2.2 


4.0 


3.5 


2.8 


2.6 


2.6 


2.7 



8.5 



0.3 


0.4 


0.45 


0.55 


1.55 


1.4 


84.4 


87.8 


85.2 


87.4 


82.2 


84.0 


1775 


1775 


1775 


1775 


1775 


1775 


10.0 


8.9 


7.9 


5.0 


-0.2 


-1.4 


1.23 


1.29 


1.42 


1.49 


1.81 


2.00 


32.1 


36.5 


38.6 


42.25 


51.4 


57.6 



13.7 



20.2 



31.5 



59.6 



79.5 



Minus values indicate weight loss on preheating greater than ASTM moisture values, 



DRYING AND PREHEATING COALS BEFORE COKING 



25 



TABLE E - RESULTS OF COKING TESTS ON HIGH-VOLATILE A BITUMINOUS COAL (WEST VIRGINIA EAGLE) 





Condition of coal 


As rec'd. 


Air dried 


Heat dried 
at 210° F 


Preheat 
at 290° F 


Preheat 
at 345° F 


Preheat 
at 435° F 


Run number 


1152 E 


1153 E 


1154 E 


1157 E 


1156 E 


1155 E 



Coking time (hr :min) 



14:50 



16:15 



14:25 



14:20 



13:50 



12:00 



Bulk density (dry coal; 
lb per cu ft) 



43.9 



47.9 



45.75 



45.9 



45.6 



Coke physical properties 
Tumbler test 
Stability 
Hardness 



Shatter test 


(%) 




+ 2" 








+ 1V 








+1" 








Sizing 


(%) 






+ 4" 








4" x 


3" 






3" x 


2" 






2" x 


1" 






1" X 


h" 






-V 








Average size 


(in 


) 


Apparent gravity 





Coke yields (% of dry coal) 
Total coke (dry) 
Furnace (+1") (dry) 
Nut (1 M x V') (dry) 
Breeze (-%") (dry) 



43.7 


45.2 


46.8 


48.7 


49.6 


52.1 


63.2 


66.2 


65.9 


65.5 


65.2 


63.9 


63 


55 


57 


64 


59 


60 


87 


85 


85 


86 


86 


86 


95 


95 


94 


95 


95 


95 


4.4 


3.5 


5.6 


6.6 


4.7 


5.3 


25.6 


24.5 


23.1 


23.2 


26.1 


24.4 


43.3 


45.0 


44.8 


43.7 


43.0 


45.1 


21.0 


21.5 


21.0 


21.2 


21.4 


20.3 


2.6 


2.5 


2.6 


2.2 


2.1 


2.1 


3.1 


3.0 


2.9 


3.1 


2.7 


2.8 


2.52 


2.47 


2.52 


2.54 


2.54 


2.55 


0.81 


0.85 


0.825 


0.815 


0.82 


0.80 


71.5 


71.6 


71.0 


71.4 


71.6 


70.3 


67.5 


67.7 


67.1 


67.7 


68.2 


66.9 


1.8 


1.7 


1.8 


1.5 


1.5 


1.4 


2.2 


2.2 


2.1 


2.2 


1.9 


2.0 



Tar yield (gal dry tar; 
per ton dry coal) 



10.7 



11.0 



11.5 



9.3 



10.5 



11.6 



Expansion pressure 
(lb per sq in.) 

Pulverization (-1/8") 

Coke temperature (° F) 

7o moisture in coal as charged 

Coke oven capacity 

Coal charges/oven/24 hr 
Lb furnace coke/cu ft/ 

24 hr 
7 increase in furnace coke 
(compared with coal 
"as received") 



0.3 


0.45 


0.4 


0.55 


0.6 


0.55 


90.9 


90.5 


90.7 


89.3 


90.8 


91.7 


75 


1775 


1775 


1775 


1775 


1775 


3.2 


2.0 


1.4 


0.0 


-0.4 


-0.5 


1.62 


1.48 


1.66 


1.67 


1.73 


2.00 


48.0 


48.0 


51.0 


51.4 


54.1 


61.0 



7.1 



12.7 



27.1 



Minus values indicate weight loss on preheating greater than ASTM moisture values. 



26 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 423 

TABLE F - ANALYSES OF COKES PRODUCED (IN PERCENT) 



Coal coked 


Volatile 
matter 


Fixed 
carbon 


Ash 


Sulfur 



High-volatile C Bituminous 
(111. No. 6) 

As received 

Air dried 

Heat dried at 210° F 

Preheated to 255° F 

Preheated to 360° F 

Preheated to 428° F 



0.8 
0.8 
1.4 
1.1 
1.0 
1.1 



88.5 


10.7 


1.76 


88.8 


10.4 


1.79 


86.8 


11.8 


1.86 


87.3 


11.6 


1.77 


88.5 


10.5 


1.74 


88.2 


10.7 


1.75 



High-volatile B Bituminous 
(111. No. 5) 

As received 

Air dried 

Heat dried at 210° F 

Preheated to 225° F 

Preheated to 313° F 

Preheated to 433° F 

Preheated to 440° F 



1.3 
1.5 
1.1 
1.3 
1.9 
1.6 
1.3 



87.9 


10.8 


1.24 


87.8 


10.7 


1.26 


88.6 


10.3 


1.21 


88.3 


10.4 


1.29 


87.8 


10.3 


1.24 


87.7 


10.7 


1.39 


88.4 


10.3 


1.19 



High-volatile B Bituminous 
(111. No. 6-A) 



As received 
Air dried 

Heat dried at 218° F 
Preheated to 227° F 
Preheated to 270° F 
Preheated to 332° F 
Preheated to 370° F 
Preheated to 450° F 



1.5 



87.9 


11.0 


0.94 


87.5 


11.3 


0.95 


87.0 


11.3 


0.93 


87.3 


11.3 


0.98 


86.7 


11.5 


0.96 


87.0 


11.4 


0.97 


88.0 


10.6 


1.03 


87.8 


10.7 


0.94 



High— volatile B Bituminous 
(111. No. 6-B) 

As received 

Air dried 

Heat dried at 213° F 

Preheated to 230° F 

Preheated to 360° F 

Preheated to 440° F 



1.2 
1.4 
1.5 
1.3 
1.2 
1.5 



88.2 


10.6 


0.75 


88.3 


10.3 


0.72 


88.3 


10.2 


0.79 


88.2 


10.5 


0.78 


88.5 


10.3 


0.76 


88.1 


10.4 


0.78 



High-volatile A Bituminous 
(West Virginia Eagle) 

As received 

Air dried 

Heat dried at 210° F 

Preheated to 290° F 

Preheated to 345° F 

Preheated to 435° F 



0.6 
1.2 
0.9 
1.1 
1.1 
0.9 



93.8 


5.6 


0.61 


93.2 


5.6 


0.56 


93.3 


5.8 


0.60 


93.2 


5.7 


0.55 


92.9 


6.0 


0.57 


93.2 


5.9 


0.54 



Illinois State Geological Survey Circular 423 
26 p., 11 figs., 1 table, app., 1968 



Printed by Authority of State of Illinois, Ch . 127, IRS, Par. 58.25 



CIRCULAR 423 

ILLINOIS STATE GEOLOGICAL SURVEY 

URBANA